1. Field of the Invention
The invention relates to an implantable mammary prosthesis adapted to combat the formation around it of a retractile shell in reaction to a foreign body, comprising a flexible pocket having a generally circular base and made from a biocompatible film material filled out to a dome shape by filling it with an appropriate fluid.
2. Description of the prior art
Broadly speaking, conventional implantable mammary prostheses are divided into two categories: the so-called pre-filled prostheses which contain a silicone gel to maintain the dome shape of the pocket even before implantation, and the so-called inflatable prostheses which are formed to shape in situ by injecting a physiologically acceptable liquid of the physiological serum type.
Nevertheless, whichever category of prosthesis is used, its implantation leads to a foreign body reaction in the organism, this reaction manifesting itself in the formation of a living membrane made up of, among other things, fibroblast collagen and myofibroblasts which completely surround the prosthesis and isolate it from the organism.
In 70 to 80% of cases this membrane remains thin and flexible and does not lead to any modification of the shape or consistency of the fitted prosthesis.
In 20 to 30% of cases, however, over a period of months or years following implantation the membrane thickens and retracts to form a shell approximating the shape of a sphere to a greater or lesser degree. This geometrical shape is, of course, that for which the surface area to volume ratio is minimal. It goes without saying that the formation of a retractile shell of this kind is the opposite of the esthetic result looked for.
At the time of writing the problem raised by the risk of a retractile fibrous shell of this kind forming has not found a satisfactory solution. All attempted solutions relating to the membrane, to the content of the prosthesis, to the nature of the surface of the pocket and to the anatomical positioning of the prosthesis have proved unsatisfactory.